you cant get your account by just knowing the name, if you have linked your account to a gmail and you still have that gmail account just add it to your phone and switch to that account - that should load your old account. if you didnt link your account or you dont remember either the name or the password of the gmail, im afraid you cant get your old account back. in any way, ask support - in my case they helped me (they are not useless)

Actually they are useless,did happen to me as well, I did have 2accounts one linked 2nd played as a guest after my tablet broke I lost access to the second account.
I have been told if I say the date of registration of the account,last order details and country of registration they will recover it for me.
But who on earth should remember something you start to play like 2 and half years ago,for second I did send them screenshots of the purchase made by my Google play account- they haven't been bothered.
Good game, but very litle support from them.
With the other games I did ever need to recover an account,the experience was much pleasant